1. Field of the Invention
The present invention relates to a modified hydrophobic textile product. More particularly, the present invention relates to a textile product having desirable properties such as a high hygroscopicity as well as an ammonia deodorizing property, an SR soil resistance, and an antistatic property, which is obtained by graft polymerization of a hydrophobic textile product with a radical polymerizable compound such as an ethylenically unsaturated organic acid, and a method for producing the same.
The term "textile product" as used herein refers to fiber or a product obtained by processing fiber, including staple fiber, cotton, tow, filament, false-twisted yarn, blended yarn, conjugate yarn, spun yarn, woven fabric, knitted fabric, and nonwoven fabric, as well as those using the same including clothing, floor coverings, interior goods, bedding, and the like. The term "cotton" as used herein refers to a physical form of a fiber which has a form similar to a natural cotton ball.
2. Description of the Related Art
Hydrophobic fiber (the term "hydrophobic fiber" is used herein in the singular, although it is intended to include a plurality of fiber materials as defined below) such as a polyester fiber and a polyamide fiber is sued in a wide variety of applications ranging from clothing to industrial materials, for its advantageous physical and chemical properties and low cost. However, due to the inherent characteristics thereof, hydrophobic fiber is relatively poor in water absorbing property and hygroscopicity, and therefore has problems as follows: it is easily electrically charged; oily soil easily attaches to it and difficult to remove therefrom; it is easily resoiled during washing; it has substantially no deodorizing property; etc. These problems are more pronounced especially when it is used in textile applications. For example, due to the substantially no water absorbing property or hygroscopicity, a textile product made of hydrophobic fiber is not comfortable when worn, as the product may get sticky and make the wearer feel hot and sweaty, while it may easily be electrically charged. Moreover, such a textile product is also poor in practical utility, as dust floating in the air easily attaches to it due to the static electricity, and ordinarily oily dirt also easily attaches to the product, such as lipid dirt (including dirt from hands, dirt on the collar, body grease, and the like), edible oil, machine oil, and hair dressing. Such dirt is difficult to remove by washing, and the product is easily resoiled during washing.
Conventionally, various methods have been proposed for overcoming these problems. For example, proposed methods for improving the water absorbing property and hygroscopicity of a polyester fiber include: a method which employs, in the polymerizable step, copolymerizable of various hydrophilic compounds (e.g., an alkylene glycol or polyalkylene glycol-type compound, a polyalkylene glycol denaturated polyester-type compound, or other hygroscopic compounds); a method in which such hydrophilic compounds are mixed in the reeling step; and a method in which such hydrophilic compounds are added with a binder, or the like, in an aftertreatment. In methods in which a hydrophilic compound is incorporated into a polyester fiber in the polymerizable step or in the reeling step, the product will not have a stiff feeling, and a desirable washing resistance is obtained. However, when the amount of the additive is increased in order to provide a sufficient hygroscopicity, the mechanical properties inherent to a polyester fiber are deteriorated, while substantially reducing the reelability. Therefore, these methods have only been used in limited applications where improving only the hygroscopicity is acceptable. On the other hand, in methods in which a hydrophilic compound is added in an aftertreatment, a desirable water absorbing property and hygroscopicity can be provided, but the product will have a stiff feeling and a poor washing resistance.
As a method for improving the washing resistance including the water absorbing property and hygroscopicity after washing, there has been proposed a method in which a synthetic polymer product is graft-polymerized with an ethylenically unsaturated organic acid such as acrylic acid or methacrylic acid, after which the carboxylic acid terminal introduced by the graft polymerization is converted to an alkali metal salt. However, the method of graft-polymerizing a hydrophobic polymer product with such an ethylenically unsaturated organic acid generally results in a low polymerization efficiency, and the graft polymerization is likely to be non-uniform.
Exemplary graft polymerization methods known in the art include: a two bath method in which an aqueous emulsified dispersion comprising a hydrophobic radical initiator, an initiator solvent, a swelling agent for a hydrophobic synthetic polymer, and an emulsifier, is attached to a hydrophobic synthetic polymer, and heated and washed with water so as to introduce a polymerization activity center to the polymer, after which a monomer having a double bond capable of radical polymerization is allowed to act upon the polymer (Japanese Publication for Opposition No. 45-502): and a one bath method in which an aromatic polyester product is processed with an aqueous dispersion which comprises a hydrophobic organic solvent, a hydrophobic radical initiator, a hydrophilic monomer having a double bond capable of radical polymerization, and an emulsifier (Japanese Publication for Opposition No. 48-27743). The two bath method involves complicated steps, and requires a long time. Moreover, it is difficult to perform a stable and uniform graft polymerization because of the fluctuation in the graft rate, and the non-uniformity of the graft polymerization. On the other hand, the one bath method has an advantage of being a single-step method, but results in disadvantages such as a non-uniform graft polymerization and a low graft polymerization efficiency. When the concentration of the hydrophilic monomer is increased while the bath ratio is decreased in this method, the graft efficiency can be significantly improved, but the uniformity of the graft polymerization further decreases, while the ungrafted polymer, which is a byproduct of the graft polymerization, is likely to agglutinate to the polymer product.
Also proposed in the art is a method in which a polyester crimped yarn is wound into a cheese, and a hydrophobic radical initiator, a hydrophobic organic solvent and a hydrophilic monomer are provided to allow graft polymerization (Japanese Laid-Open Publication No. 48-096894). However, the method has problems of noxious vapors and poor work environment due to the use of an organic solvent.
Moreover, it is also conventionally known in the art to use a carrier as a swelling agent for a hydrophobic polymer in the graft polymerization step, in order to improve the graft efficiency. However, the odor of the carrier is very distinctive and strong, which may remain in the final product.
In applications such as clothing, bedding, household commodities, and interior goods, the ammonia odor from sweat and urine is often the problem to be addressed.
In order to provide polyester with an ammonia deodorizing function, there has been proposed a method in which a functional agent having an ammonia deodorizing property is added in an aftertreatment. However, the product produced according to this method has a stiff feeling and a poor washing resistance.
It is thought that the durability of a fiber or a textile product can be improved by graft polymerization of an organic acid monomer. However, the mechanical properties of the fiber are substantially deteriorated by the graft polymerization. When an introduced acidic group is converted to a metal salt in order to improve the hygroscopicity, the ammonia deodorizing function is decreased. Thus, it has not been possible in the art to improve both the ammonia deodorizing property and the hygroscopicity.